TMSS
was it legal outside the US?

The way the Trademark security system worked was that certain company names would be checked at boot up, and if not present, the console would lock up. Both Nintendo and Sega used this system to give them the ability to sue unlicensed game makers for trademark infringements if they got their games to boot. When Sega went to court with accolade, the legality of this system was eventually questioned, and it was ruled that these schemes did not constitute trademark infringements.

However, Sega continued using TMSS all the way until the dreamcast. I'm guessing that this is because while these systems didn't hold up in the US, they might have held up elsewhere in the world? Anybody know why TMSS was continued to be used after Sega v Accolade?

Maybe they continued using it as a form of check that a cart was in, just because they'd already built it. From Sega's point of view, if a cart is legit it'll have the text there, so boot it. If not, who cares? It just means you don't need to unleash the packs of lawyers if some non-licensed cart connects, because at this point TMSS was less about checking for whether a cart was licensed as it was to check there's a cart present.

Maybe they continued using it as a form of check that a cart was in, just because they'd already built it. From Sega's point of view, if a cart is legit it'll have the text there, so boot it. If not, who cares? It just means you don't need to unleash the packs of lawyers if some non-licensed cart connects, because at this point TMSS was less about checking for whether a cart was licensed as it was to check there's a cart present.

Wild guess, nothing more.

No no, you misunderstand - consoles after the Genesis continued to have TMSS protections. The dreamcast boot sequence checks for the license screen graphic byte by byte upon boot, if it is altered in any way, boot fails. The Saturn has something similar. If those schemes were ruled illegal in Sega vs Accolade, yet continued to use them in subsequent consoles, all I can conclude is that they must have been legal outside the US. But I can't find any information on TMSS except from a US perspective. Anyone know otherwise?

Did the court decision in question actually rule "TMSS is illegal." or did it just rule "You can't sue unlicensed games that pass the check for Trademark."? Because that seems like the kind of nitpicking subtlety that legal types thrive on, and even if the courts gave the stricter verdict that TMSS is illegal all around, Sega might've gotten away with violating simply because they stopped suing people for having the right data to pass the check without Sega's permission(Not like the legal system keeps tabs on what businesses do unless someone complains and an unlicensed dev complaining about something like this puts the unlicensed dev under scrutiny as well).

Granted, this is just simply a wild ass guess from someone who never heard of TMSS before and whose entire knowledge of the specific subject is contained in this thread.

Basically, the use of Sega's trademark was allowed without a license because it was required for fair use.

Incidentally, the Game Boy series (GB, GBC, GBA) and Nintendo DS all had a similar check. They looked for the "Nintendo" graphic in the header. (DSi and later also check for an RSA signature, which isn't as easy to bypass. Older DS games are whitelisted, since they don't have signatures.)

The fact that both companies continued to use trademark-based security seems to imply that they thought it was still binding outside of the US. (Maybe in Japan?)

Clarification from another board reveals that the EU has no fair use exemption provisions, and thus this still constitutes a trademark violation. This makes sense per my own research, as Commodore used a TMSS scheme with their CD booting systems, and the CD32 launched in late 93.